First-degree relatives of schizophrenics have been described in the clinical literature as having certain personality abnormalities like "introversion, suspiciousness, lacking in interpersonal effectiveness..." This study selects 60 first-degree relatives of schizophrenics and a control group of 60 first-degree relatives of manic-depressives. The Research Diagnostic Criteria (RDC) system is used to select the two groups. Three personality tests, the California Psychological Inventory (CPI), the Myers-Briggs and the Cattell 16PF are used to assess the personality characteristics that may be specific to individuals biologically related to a group of schizophrenics.